Print a small batch of cheques using a regular cartridge. See if they clear without incident. If your bank's clearing office phones and says they cannot read the cheques, then apologize profusely and say you forgot to put in the magnetic toner cartridge. Then buy a small printer for which magnetic toner cartridges are available and use it exclusively for printing cheques (its a good idea to have a separate cheque printer anyway). Our magnetic toner cartridge lasted 5 years (there's not a lot of ink on a cheque).

But really - magnetic ink in 2011, in these days of speech recognition and OCR of entire scanned books? Who are they kidding?